Flexible rubber impeller pumps are used in the marine industry as raw water coolant pumps for diesel and gasoline internal combustion engines. They draw water from the lake or ocean and either pump it to the engine directly as in the case of pleasure boat engines or through a heat exchanger as in the case of larger diesel engines. The rubber impeller in this variety of a pump consists typically of an insert of a metal or plastic around which a rubber impeller incorporating a number of blades is molded. The impeller is mounted on a shaft and is driven by means of a key, spline or a flat on the shaft. In the "new" condition, the impeller is free to move axially on the shaft such that the impeller will find its center position. The rubber impeller must be periodically replaced due to wear and deterioration over time. Most manufacturers of flexible rubber impeller pumps recommend that the impeller be replaced annually before the beginning of a new boating season.
Changing an impeller at a properly equipped repair facility or marina when the boat is in port usually does not present a problem. However, often the marine engine is not serviced as specified or the impeller fails prematurely from various environmental reasons such as the pump suction being blocked or running in an adverse environment such as silt and sand. When such failures occur, the engine overheats and the boat crew is required to change the impeller on the pump under less than ideal conditions which include a hot engine and a cramped engine compartment, inadequate tools and possibly a boat which may be adrift in rough seas and foul weather. The removal of the impeller is further complicated by the presence of corrosion and build up of deposits between the impeller insert and the shaft.
The typical method for impeller removal requires the use of a pliers. After removing the cover plate on the pump housing and exposing the end of the impeller to the operator, two pairs of pliers are used by the operator to grip the blades of the impeller. A strong hold is required to remove the impeller from the pump housing. This method works reasonably well on a work bench where the mechanic can assume a good stance and use both arms to advantage. A stubborn impeller can also be assisted along by prying it with screwdrivers.
A number of removal tools have been marketed over the years to assist in the removal of rubber impellers. Typically they are similar to bearing pullers with a modification on three or four legs for gripping the impeller. These removal tools are expensive and usually found at marinas. They are rarely used by average boaters or, for that matter, found in a tool box of average boaters. The average boater must therefore rely upon his or her trusty pliers to pull the impeller from the housing, a task which can be challenging when performed over a hot engine on a rocking boat and a cramped engine well and using both hands. Therefore what is needed is a flexible impeller with an improved insert that allows it to be readily removed from the pump.
Thus, the primary object of the present invention is to provide a flexible impeller with an insert designed for easy removal of the impeller under adverse conditions, by using inexpensive items found at a hardware store or work bench as the removal tool.
A further object of the present invention is to provide a flexible impeller that can be readily removed with one hand using only a threaded tool to engage the insert of the impeller and removing the impeller by simply rotating the tool.
Yet another object of the present invention is to provide a flexible impeller with an improved design that modifies the traditional insert for securing the impeller to the pump drive shaft by including an arrangement which allows the impeller to be readily removed with a conventional threaded tool.